Bearings



Jan. 30, 1962 A. E. 5. WHITE 3,019,068

BEARINGS Filed March 5, 1959 United States Patent 3,019,06S BEARINGSAlbert Edward Sutherland White, London, England, as-

signor to The Morgan Qrucibie Company Limited,

ice

1000 C. for half an hour in air to produce a surface layer containingnickel oxide.

EXAMPLE 2 60 parts of carbonyl nickel powder (average particle ggg fi fig fggg s g fig size 5 microns) were mixed with 40 parts of nickel oxideClaims priority, application hreat Britain Mar. 7, 1958 y-gr n lboratory reagent quality) sufiiciently fine to 17 Cl i (Cl, 303. 237pass through a 300 B.S.S. screen. The mixture was wetted with water,ball milled for 24 hours, dried and intimately This invention relates tohearings or the like anti-fricmiXed ith of a Water wax emulsion soldunder the tion elements for shafts a d oth moving parts a d i registeredtrademark Mobilcer C. A bearing was then particular to bearings for useunder conditions of high pressed to Shape at a Pressure of 10 tons pSquare inch temperatures, for example, temperatures in excess of Th6formed bearing Was then heated at about 00 C. t 500 C. remove the waxslowly and then fired in an atmosphere It is the object of the inventionto provide bearings or of C erci l argon over a period of 12 hours up toa the like anti-friction elements for running under conditionstemperature of 1380-l400 C. The bearings were then of high temperature,hereinafter referred to as high temed at a ut 10 0 C. for half an hourin air to perature bearings, having a low coefiicient of slidingfricensure c p Xidi ti II of th urface. tion and having generallyexcellent running properties un- Bearings of Outside diameter insidediameter def th diti n 1%" and length 2", made according to the aboveex- In accordance with the invention the bearing surface of flmpies WereSubjected to Inning tests on a shaft of heat a high temperature bearingcontains in major proportions resisting stainless steel, which had beenStellited (Stellite nickel oxide or cobalt oxide or of both oxides. Overthe bearing Portion and heat treated at C- Generally the amount byweight of nickel or cobalt oxide for 4 hours in an oxidizing atmospheremp r in the bearing surface may lie in the range 50% to 100% Purposes, abearing made in accordance with Example 1 and preferably between 60% and100%, and a similar but unoxidized nickel-mullite bearing were The annin which th i k l o obalt o id also tested under the same conditions butrunning on an oxides are incorporated in the bearing surface is not im-Xidi d t liit d Shaft. portant, but conveniently the bearing ismanufactured from a composition containing metallic nickel or cobaltTest condmons or both and afterwards subjected to an oxidising processConstant load-200 p.s.i. or from a sintered ceramic or metal-ceramiccomposition Ambient temperature--700 C. containing at least asubstantial proportion of oxide pow- Running clearance0.025". der. Shaftspeed4.9 ft./min.

The invention is particularly applicable to bearings Operation-half anhour running, half an hour at rest, formed from sintered powders inwhich one of the powload and temperature constantly applied. ders isnickel or cobalt, for example, nickel/mullite bear- Running time(actual)-25 hours (i.e., 50 hours total ings such as are described inthe co-pending patent aptime in test rig). plication of Albert EdwardSutherland White, Serial No. 669,080, filed July 1, 1957, but bearingsin accordance Each hearing was relieved over a portion of its surfacewith the invention can be produced by casting nickel or to give 114 arcof contact between the bearing and the cobalt containing alloys,provided they are such that the shaft.

RESULTS Example 1 bearing on Example 2 bearing on Example 1 bearing onUnoxidised Ni/mullite bearoxidised shaft oxidised shaft unoxidised shaft1 ing on unoxidised shaft Average coefllcient of fric- 0.32 0.32...0.27... 0.81.

tion. Radial wear of bearings. 0.001 0.0012" 0.000 5.. 0001 Surfacefinish of bearing 120 micro inches C.L.A. 70 micro inches O.L.A. wellmicro inches C.L.A. dull 2300 micro inches C.L.A. two after test highlypolished, slight forpolished black surface. grey surface. or threepatches of welding Surface finish of shaft after test +9 mation of hardblack layer. 120 micro inches C.L.A. very highly polished no wear.

70 micro inches C.L.A. well polished black surface no wear.

and Stcllitc build up.

Badly serrated with two deep scores.

1 This bearing vibrated somewhat during running.

2 +=Mcasurcd by a Talysurf surface roughness measuring machine.

Norm-The thickness of the oxide film in Example 2 is 8 microns.

EXAMPLE 1 Nickel-mullite (75 :25) bearings were made as described inExample 2 of the aforementioned co-pending patent application Serial No.669,080, and were then heated at about O.L.A.=centre line average.

The following examples specify the compositions and methods of treatmentto produce an oxide film on the bearing surfaces of a variety of testspecimens. Each specimen incorporated a flat bearing surface and testswere carried out by running an annulus of Stellite 12 counterfacematerial (oxidised at 1000 C. for half an hour) of approximately 1diameter and hi well thickness against the bearing surface of eachspecimen under a pressure of 300 lbs./ sq. in. and at a speed of 22 ft.per minute at the area of contact. The ambient temperature was 700 C.

The bearing materials tested were:

Example 3 .-Cast nickel on which a nickel oxide film 3 was developed byheating in air of 1% hours at 1000 C.

Example 4.Monel (Cu 30%, Fe 1.4%, Mn 1.0%, balance Ni) on which an oxidefilm was developed by heating in air for /2 hour at 1000 C.

Example 5.Inconel (Cr 13%, Fe 6.5%, balance Ni) on which a nickel oxidefilm was developed by heat ing in air for 6 hours at 1000 C.

Example 6.-Sintered nickel oxide prepared by sintering a pressed nickeloxide powder body at 1600 C. in air.

Example 7.-Nickel+25% magnesia made by ball milling 300 mesh nickel andmagnesia powders, waxing, pressing and sintering at 1380-1400 C. in asimilar manner to that described in Example 2. The surface was thenoxidised by heating for /2 hour in air at 100 C.

Examples 810.Nickel+25%, 40%, and 50% mullite respectively made andoxidised in a similar manner to that described in Example 7.

Example 1].Cobalt-|-25% mullite, made and oxidised in a similar mannerto that described in Example 7.

The results of the tests on the specimen were as follows:

Oxide film Ex. Material (oxidised) thickness Coetf. of Comments No.(microns) friction 3 Cast nickel 9 .34 Oxide film tended to break downtowards the end of the test. 4... Monel 5 .51 Unsatisfactory. Poor oxidefilm. 5.--... Inconel 4 .36 Fairly satisfactory operation. 6 sinterednickel oxide. .35 Good smooth operation. 7. Sintered Ni+25% 7 .37 D0.

MgO. 8-- Sintered Ni+25% 5 .32 Do.

mullitc. 9"-.- Sintered Ni+40% 7 .36 Do.

mullitc. 10..-- sintered Ni+50% 4 .42 Some surface cracks mullite. aftertest. 11..-- sintered cobalt +25% 9 .30 Good smooth operamullite. tion.

Generally comparable results were obtained using counterface materialssuch as, for example, chromium plated steel or high temperatureresistant stainless steel, and Stellite 12 unoxidised.

Examples of anti-friction elements according to the invention are shownin the accompanying drawings in which FIG. 1 shows a bearing and FIG. 2shows a sealing ring in which the surface contains a substantialproportion of nickel or cobalt oxide.

What is claimed is:

1. A bearing assembly comprising two relatively movable elements incontact, the contacting area of at least one of the elements containingat least 50% of at least one material selected from the group containingnickel oxide and cobalt oxide.

2. A bearing assembly comprising two relatively movable elements incontact, the contacting area of at least one of the elements containingat least 60 percent of at least one material selected from the groupcontaining nickel oxide and cobalt oxide.

3. A bearing assembly comprising two relatively movable elements incontact, at least one of said elements being manufactured from acomposition containing at least 50% of at least one material selectedfrom the group containing nickel oxide and cobalt oxide.

4. A bearing assembly comprising two relatively movable elements incontact, at least one of said elements being manufactured from acomposition containing at least 60 percent of at least one materialselected from the group containing nickel oxide and cobalt oxide.

5. A bearing assembly according to claim 4 in which said composition ismade of sintered powders of at least one material selected from thegroup containing nickel oxide and cobalt oxide and a ceramic material.

6. A bearing assembly according to claim 5 in which the ceramicrmaterialis mullite.

7. A bearing assembly comprising two relatively movable elements incontact, at least one of said elements being made of a sintered powderof a material selected from the group containing nickel oxide and cobaltoxide.

' 8. A bearing assembly comprising two relatively movable elements incontact, at least one of said elements being manufactured from acomposition containing at least 50% of at least one metal selected fromthe group containing nickel and cobalt and having an in situ surfacelayer of oxide.

9. A bearing assembly comprising two relatively movable elements incontact, at least one of said elements being manufactured from acomposition containing at least 60% of at least one metal selected fromthe group containing nickel and cobalt and having an in situ surfacelayer of oxide.

10. A bearing assembly according to claim 9 in which said composition ismade with sintered powders of the metal and a ceramic material.

11. A bearing assembly according to claim 10 wherein the ceramicmaterial is mullite.

12. A bearing assembly comprising two relatively movable elements incontact, at least one of said elements being manufactured from asintered body of at least one metal powder selected from the groupcontaining nickel and cobalt and at least one powder of a materialselected from the group containing nickel oxide and cobalt oxide, thesintered body having an in situ surface layer of oxide.

13. A bearing assembly comprising two relatively movable elements incontact, at least one of said elements being manufactured from asintered body of nickel powder and powdered magnesia, the amount ofnickel powder being at least 50 percent by weight of the sintered bodyand having an in situ surface layer of oxide.

14. A method of treating an anti-friction element of a bearing assemblycomprising two anti-friction elements in relatively movable contact,said anti-friction element to be treated containing at least 50% of atleast one metal selected from the group containing nickel and cobaltcomprising subjecting said anti-friction element to surface oxidation toform an oxide in situ on the element surface which is in contact withthe other element of the bearing assembly.

15. A method of treating an anti-friction element of a bearing assemblycomprising two anti-friction elements in relatively movable contact,said anti-friction element to be treated containing at least 60% of atleast one metal selected from the group containing nickel and cobaltcomprising subjecting said anti-friction element to surface oxidation toform an oxide in situ on the element surface which is in contact withthe other element of the bearing assembly.

16. A method of treating an antifriction element of a bearing assemblycomprising two anti-friction elements in relatively movable contact,said anti-friction element to be treated being from a sintered body ofat least one metal powder selected from the group containing nickel andcob-alt and at least one powder of a material selected from the groupcontaining nickel oxide and cobalt oxide, comprising subjecting saidanti-friction element to surface oxidation to form an oxide in situ onthe element surface which is in contact with the other element of thebearing assembly.

17. A method of treating an anti-friction element of a bearing assemblycomprising two anti-friction elements in relatively movable contact,said anti-friction element to be treated being from a sintered body ofnickel powder and powdered magnesia, the amount of nickel powder beingat least 50 percent by weight of the sintered body, comprisingsubjecting said anti-friction element to surface oxidation to form anoxide in situ on the element surface which is in contact with the otherelement of the bearing assembly.

References Cited in the file of this patent UNITED STATES PATENTS 6Bennett Apr. 28, 1931 Linder Sept. 20, 1932 Singer Jan. 11, 1938 HenselMar. 27, 1945 Stupakofi? Dec. 17, 1946 Smith Jan. 9, 1951 Daniels Nov.29, 1955

1. A BEARING ASSEMBLY COMPRISING TWO RELATIVELY MOVABLE ELEMENTS INCONTACT, THE CONTACTING AREA OF AT LEAST ONE OF THE ELEMENTS CONTAININGAT LEAST 50% OF AT LEAST ONE MATERIAL SELECTED FROM THE GROUP CONTAININGNICKEL OXIDE AND COBALT OXIDE.